Looking for advice—I’d like to track down somone who threatened me online

I write a conservative blog on my town’s online newspaper. A commenter wrote that I should be shot.

I have the IP address—is there any way I can track down who sent the message? At the very least, if I can put some heat on the Internet provider, I can make the dude’s life uncomfortable., and perhaps dissuade him (?) from doing it again. Any ideas?